1. Field of the Invention
The present invention relates generally to heat exchangers and, more specifically, to a tube and chamber apparatus for transporting heat exchange media.
2. Discussion of the Related Art
Heat exchangers are commonly utilized in systems where it is desired for heat to be removed. Typical basic heat exchangers are made of pipes, which channel heat exchanging media. Headers or manifolds are attached to each end of the pipes. These headers and manifolds act as receptacles for the heat exchanging media. The efficiency of the pipe heat exchangers is limited by the amount of surface area available for the transfer of heat.
To add more surface area, some heat exchangers, such as condensers, incorporate a “tube-and-fin” design. This type of heat exchanger typically includes flattened tubes having a fluid passing therethrough and a plurality of fins extending between the tubes. The fins are attached to the tubes to effectively increase the surface area of the tubes, thereby enhancing heat transfer capability of the tubes. A number of tubes and fins may be stacked on top of each other, which leaves a small opening to allow passage of air in between them. In another tube-and-fin design, the tube can be of a serpentine design, therefore eliminating the need for headers or manifolds, as the tube is bent back and forth in an “S” shape to create a similar effect. Typical applications of this type of heat exchanger, besides condensers, are evaporators, oil coolers, and heater cores. This tube-and-fin design is also utilized in radiators for automobiles. Outside of the automotive field, the tube and fin design is implemented by industrial oil coolers, compressor oil coolers, and in other similar applications requiring a higher efficiency heat exchanger.
In another effort to create a greater exchange of heat by increasing surface area, very thin flat tubes with intricate inner rib structures are utilized. This type of heat exchanger is similar to the tube-and-fin design, in that fins are combined with the flat tubes, but in this particular type of heat exchanger, the flat tubes contain intricate internal chambers formed by the inner rib structures. These inner rib structures help to increase the heat exchanging performance of the heat exchanger. To further improve heat transfer efficiency, the tube thickness is made thinner. As a result, the parts are lighter in weight, which in turn makes the overall heat exchanger lighter in weight. However, the pressure resistance is reduced, and the thinner tubes are more prone to damage. Also, the assembly process is complicated because of the fragile nature of the parts. In addition, the internal chambers are prone to plugging during the manufacturing process, particularly if a brazing process is utilized. The complexity of the extruding process potentially results in higher costs and higher defect rates. Also, by utilizing internal chambers within the flat tubes to help disperse heat, the overall cost for the heat exchanging system will be higher because a higher powered compressor may be necessary to move the heat exchanging medium through the smaller openings of the tubes. Conversely, if a higher powered compressor is not utilized, then additional tubes will be necessary to obtain the desired heat exchanging performance because the smaller tubes reduce the flow of the heat exchange media significantly. The additional tubes will increase the overall cost for the heat exchanging system. Currently, this type of heat exchanger is used in applications requiring high heat exchanging capabilities, such as automotive air conditioner condensers.
A variation on the tube-based heat exchanger involves stacking flat ribbed plates. When stacked upon each other, these ribbed plates create chambers for transferring heat exchanging media. In essence, this type of heat exchanger performs substantially the same function as tube-and-fin type heat exchangers, but is fabricated differently. This type of heat exchanger is commonly implemented by contemporary evaporators.